The invention concerns an electric alarm watch, particularly an electric wristwatch with alarm device, with an electric movement driven by drive impulses, as well as an electric signal source.
Electric wristwatches of this type are known (see for instance DT-OS 1, 673, 697 and the magazine "Die Uhr", No. 13, 1972, page 100) with the electric signal source consisting of a battery, an electric-excited buzzer and the watch crystal; part of the buzzer is a leaf spring excited in its natural frequency which strikes against a pivot fastened at the watch crystal and thereby causes the watch crystal to vibrate.
This known construction has several disadvantages: in the first place it is sumptuous in view of the number of parts, because a buzzer of this type requires two coils. The buzzer must be of very accurate construction and needs adjustment, so that the leaf spring can be excited in its natural frequency. Finally, the small dimensions of a wristwatch condition relatively high frequencies of the leaf spring, so that this known wristwatch dispenses a relatively high-frequency sound which is often not heard.
The object of the invention is to construct a watch of the type mentioned at the beginning to be of simpler construction than the previously described, known type. This problem is solved in accordance with the invention by the fact that the signal source can be applied to voltage drained off the drive impulses or the alarm device can be controlled by impulses from a frequency divider in an electronic watch such as is shown in U.S. Pat. No. 3,540,209 issued Nov. 17, 1970 to N. C. Zatsky and assigned to same assignee as the present invention. Disregarding synchronous watches, impulses are produced for the drive of the electric movement in all electric watches, these impulses, in accordance with the invention, are also used for operating the signal source. One can, for instance, in an electric quartz watch extract impulses at any chosen step of the frequency divider, switches after the quartz, which after corresponding amplifying can be used for operating the signal source. This can be of simple construction, since for instance only one single coil, a permanent magnet and a vibrating organ will suffice for producing vibrations for the alarm signal. The basic idea of the invention can also be applied to electric movements with a balance wheel by amplifying the drive impulses for the balance wheel, which have for instance a pulse repetition frequency of 6 Hz, and connecting same to a suitable signal source. It is the low pulse repetition frequency with balance wheel watches which leads to a distinctive signal, and it is a special characteristic of a preferred type of construction in accordance with the invention that impulses with a pulse repetition frequency of approximately 5 - 10 Hz, particularly 6 Hz, can be applied to the signal source. This is quite contrary to the known watches of the type mentioned, whose alarm signal is always of considerably higher frequency.
In view of the invention a simplification in construction over prior art watches can be achieved, particularly with electric balance wheel watches having a drive coil on the balance wheel and a stationary permanent magnet, thereby that the permanent magnet for the drive of the movement is also a part of the signal source, which means saving a separate permanent magnet for operating the signal source. This will also allow a very flat watch construction, which is of special importance with wristwatches.
With a preferred type of construction of the invention, the watch crystal is included in the electro-mechanical transducer system, as is known, and the thinnest construction conceivable is achieved by arranging in the signal source the permanent magnet of the watch movement between a balance wheel equipped with coil and a vibrator equipped with coil, which is rotary positioned around an axis running vertically to the watch crystal and strikes against stops formed at the watch crystal or fastened to this.